Ulster Bank has said it has now resolved the problem which yesterday left around 600,000 customers out of pocket.

In a statement the bank said it apologised for the error.

Yesterday Ulster Bank had been forced to offer emergency cash payments after another shambles meant funds have disappeared from the accounts of thousands of customers.

A spokesperson for the bank claimed it was not an IT issue. A payment file did not process overnight as a result of human error, it said.

The bank said that Ulster Bank was among the banks benefiting from €1.14bn spent every year by its parent Royal Bank of Scotland on technology and innovation.

Ulster Bank yesterday did not say how many customers were affected, but stressed that not all of those with a current account had seen their funds disappear.

“We are investigating this issue as a matter of urgency and apologise for any inconvenience caused. No customer will be left out of pocket as a result of this issue. Emergency cash is available in branch or via telephone,” the bank said.

The Central Bank is now reviewing the latest in a string of accounts problems to hit the bank, which has around 600,000 current accounts.

The bank has been accused of failing to invest in its payments systems.

Large numbers of the bank’s customers reported that their salaries have vanished from their accounts, while direct debits have not been paid.

Other customers have reported that credit and debit cards have been declined.

Customers said when they checked their accounts online, their balances were not as they should be.

Lodgements of cheques and the like are not showing up in current accounts.

Customers said transactions since Friday were missing.

Hundreds of frustrated customers took to Twitter yesterday to complain.

“My salary has disappeared from my account today and my wife had her card declined when trying to pay for a GP visit and medication. Extraordinary how often this kind of issue happens with this bank. Time to change to a competitor I think,” one customer said.

Finance Minister Paschal Donohoe said it was a very concerning development. He said the Central Bank was reviewing the matter.

“It is a real worry for anybody, caused a lot of panic and it is really important that Ulster Bank gives the assurance that nobody will be out of pocket,” he said.

Fianna Fáil finance spokesman Michael McGrath said the fact that Ulster Bank customers have again been affected by a payments system failure meant there was a need for the Central Bank to now conduct a comprehensive review of the systems used by retail banks here.

“These IT failures are happening all too often at Ulster Bank and the question has to be asked if it is the result of a lack of investment by the bank. It is every bank’s responsibility to ensure that its IT systems are fit for purpose.”

The Oireachtas Finance Committee is to call in the bank’s executives and the Central Bank to explain what happened, following a suggestion from Sinn Féin finance spokesman Pearse Doherty.

The Central Bank said it was “aware of an issue involving the bank accounts of certain Ulster Bank customers”. It said it was monitoring the situation.

The Financial Services Union general secretary Dermot Ryan said that the mess served as a further reminder of the fragility of an over-reliance on technology and the impact on customers.

Ulster Bank had offered customers affected by the disappearance of money from their accounts the option of getting emergency cash.

The bank says it is investigating how money has gone missing from customer current accounts.

And it promised that no affected customer would be left out of pocket.

It said it would be making emergency cash of up to €500 available to customers who needed it.